GLUCOREGULATION AND HORMONAL RESPONSES TO MAXIMAL EXERCISE IN NON-INSULIN-DEPENDENT DIABETES

Maximal dynamic exercise results in a postexercise hyperglycemia in healthy young subjects. We investigated the influence of maximal exercise on glucoregulation in non-insulin-dependent diabetic subjects (NIDDM). Seven NIDDM and seven healthy control males bicycled 7 min at 60% of their maximal O2 consumption (V̇O2(max)), 3 min at 100% V̇O2(max), and 2 min at 110% V̇O2(max). In both groups, glucose production (R(a)) increased more with exercise than did glucose uptake (R(d)) and, accordingly, plasma glucose increased. However, in NIDDM subjects the increase in R(a) was hastened and R(d) inhibited compared with controls, so the increase in glucose occurred earlier and was greater [147 ± 21 to 169 ± 19 (30 min postexercise) vs. 90 ± 4 to 100 ± 5 (SE) mg/dl (10 min postexercise), P < 0.05]. Glucose levels remained elevated for > 60 min postexercise in both groups. Glucose clearance increased during exercise but decreased postexercise to or below (NIDDM, P < 0.05) basal levels, despite increased insulin levels (P < 0.05). Plasma epinephrine and glucagon responses to exercise were higher in NIDDM than in control subjects (P < 0.05). By use of the insulin clamp technique at 40 μU · m-2 · min-1 of insulin with plasma glucose maintained at basal levels, glucose disposal in NIDDM subjects, but not in controls, was enhanced 24 h after exercise. It is concluded that, because of exaggerated counter-regulatory hormonal responses, maximal dynamic exercise results in a 60-min period of postexercise hyperglycemia and hyyperinsulinemia in NIDDM. However, this event is followed by a period of increased insulin effect on R(d) that is present 24 h after exercise.